Ok, symptoms are;
30mph+, droning noise starts and gets louder up to about 60mph.
I've got a spare set of wheels and tyres, so changed those in case it was tyre noise - no change.
At 50mph, I can switch off the engine, then turn the ignition so I've still got steering etc, droning is still there, so rules out engine noises I guess.
The droning drops with road speed.
Local VAG specialist thought it could be a wheel bearing, so spent today dismantling the drive shafts on the front so he could listen to the hubs/bearings, thought the OSF was noisy so changed the wheel bearing - droning still there... Aaargh!!
So, I'm left with changing the left hand side, or turning my attention to the expensive oily bit called the gearbox and differentials! The noise is definately road speed related though, it doesn't change pitch with changing gears or anything. It's still there with the engine switched off, in neutral and coasting to a stop. Could it be prop shaft bearings (I confess I don't even know if there are any!) or even CV joints or similar?
I did try the long left or right sweeper test to see if the droning changed pitch under left or right cornering, and I'd kind of convinced myself it changed when I went round right handers, but not sure really.
Any pearls of wisdom before I chuck even more money at this thing?! HELP!!!!